Astrophysics: Wolf-Rayet Stars
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Questions and Answers

What are Wolf-Rayet stars primarily characterized by?

  • High mass loss rates (correct)
  • Low luminosity
  • High variability
  • Low temperatures
  • Who discovered Wolf-Rayet stars?

    C.J.E. Wolf and G. Rayet

    More than 220 Wolf-Rayet stars have been identified.

    True

    What are the wind speeds of Wolf-Rayet stars?

    <p>800 to 3000+ kilometers per second</p> Signup and view all the answers

    What is AB7 also known as?

    <p>SMC WR7</p> Signup and view all the answers

    Which star is classified as a luminous blue variable?

    <p>AG Carinae</p> Signup and view all the answers

    AG Pegasi is a binary system composed of a red giant and a white dwarf.

    <p>True</p> Signup and view all the answers

    What is the approximate location of CD Crucis?

    <p>Crux</p> Signup and view all the answers

    What is the composition of HD 38282?

    <p>Two hydrogen-rich Wolf-Rayet stars</p> Signup and view all the answers

    R136a1 is known for being one of the most massive stars at what mass?

    <p>215 M☉</p> Signup and view all the answers

    What makes hypernovae distinct?

    <p>Produced when a very massive star collapses into a black hole</p> Signup and view all the answers

    Study Notes

    Wolf-Rayet Stars

    • Discovered by C.J.E. Wolf and G. Rayet at Paris Observatory in 1867, with over 220 identified.
    • Characterized by extremely high temperatures ranging from 25,000 to 100,000 K.
    • Experience mass loss exceeding 10^-5 Solar masses per year.
    • Wind speeds can reach between 800 to over 3,000 kilometers per second.
    • Typically exhibit rapid rotation and can start from masses under 20 Solar masses; lack dramatic variability.

    AB7

    • Known as SMC WR7, this binary star is found in the Small Magellanic Cloud.
    • Comprises a Wolf-Rayet star and a supergiant companion of spectral type O with a 19.56-day orbital period.
    • Surrounded by a bubble nebula.

    AB8

    • Also referred to as SMC WR8, a binary star in the Small Magellanic Cloud.
    • Consists of a Wolf-Rayet star and a main sequence companion of spectral type O, orbiting every 16.638 days.
    • Notable for being one of only nine known WO stars and the only one in the SMC not on the nitrogen sequence.

    AG Carinae

    • A luminous blue variable star in the constellation Carina.
    • Recognized as one of the most luminous stars in the Milky Way.

    AG Pegasi

    • A symbiotic binary star located in the constellation Pegasus, composed of a red giant and a white dwarf.
    • The primary has a mass of approximately 2.5 Solar masses, while the secondary is around 0.6 Solar masses.
    • Classified as a symbiotic nova with a history of outbursts.

    Apep

    • A triple star system located in the constellation Norma, including a Wolf-Rayet binary and a hot supergiant.
    • Named after the Egyptian serpent deity and surrounded by stellar wind and cosmic dust forming a "pinwheel" shape.
    • Identified as a prominent gamma-ray burst progenitor candidate in the Milky Way.

    Arches Cluster

    • The densest known star cluster in the Milky Way, situated about 100 light-years from its center in Sagittarius.
    • Discovered in 1995 and obscured by heavy optical extinction; observed in X-ray, infrared, and radio bands.
    • Home to approximately 135 young, massive stars, alongside thousands of less massive stars.

    BAT99-98

    • A massive star located in the Large Magellanic Cloud, near the R136 cluster in the 30 Doradus nebula.
    • Rated at 226 Solar masses and 5,000,000 Solar luminosities, making it one of the most massive and luminous stars.

    CD Crucis

    • Known as HD 311884, an eclipsing binary star in the constellation Crux, approximately 14,000 light-years away.
    • Contains a Wolf-Rayet star, also designated WR 47.

    Cygnus X-3

    • A high-mass X-ray binary (HMXB) considered a microquasar.
    • The only known HMXB with a Wolf-Rayet star, pulling gas from an ordinary star companion.
    • Invisible to the naked eye; observable in radio, infrared, X-ray, and gamma-ray spectra.

    EZ Canis Majoris

    • A binary system in Canis Major, highlighted as one of the ten brightest Wolf-Rayet stars.
    • Its primary Wolf-Rayet star shines at an apparent magnitude brighter than 7.

    Gamma Velorum

    • A quadruple star system in the constellation Vela, one of the brightest stars with a combined magnitude of +1.7.
    • Contains the closest and brightest Wolf-Rayet star, known traditionally as Suhail al Muhlif, and modernly as Regor.

    GCIRS 13E

    • An infrared and radio object near the galactic center, suspected to be a cluster of hot massive stars.
    • Potentially harbors an intermediate-mass black hole at its core.

    GCIRS 16SW

    • A contact binary star in the Galactic Center, with both stars of equal size in orbit every 19.5 days.
    • Atmospheres overlap, creating an eclipsing binary with a brightness variation of 0.35 magnitudes in infrared.

    HD 5980

    • A multiple star system located in NGC 346 within the Small Magellanic Cloud and recognized as one of its brightest stars.

    HD 38282

    • A massive spectroscopic binary star located within the Tarantula Nebula, made up of two hydrogen-rich Wolf-Rayet stars.

    HD 97950

    • A multiple star system classified initially as a single star but revealed to be a massive star cluster in the NGC 3603 region.

    HD 151932

    • A Wolf-Rayet star in the constellation Scorpius, located about 1,300 parsecs from Earth.
    • Extremely reddened by interstellar extinction; one of the few visible Wolf-Rayet stars to the naked eye.

    Hypernova

    • Generated when a very massive star collapses into a black hole.
    • Considered a potential source of gamma-ray bursts.

    LH41-1042

    • A Wolf-Rayet star in the Large Magellanic Cloud and a rare member of the WO oxygen sequence.

    LMC195-1

    • Another Wolf-Rayet star in the Large Magellanic Cloud, classified as a WO2, likely among the hottest stars known.

    Melnick 34

    • A binary Wolf-Rayet star located near R136 in the 30 Doradus complex, consisting of highly luminous components.

    Romano's Star

    • A luminous blue variable star in the Messier 33 galaxy, situated in the constellation Triangulum.

    Theta Muscae

    • A multiple star system in Musca, recognized as the second-brightest Wolf-Rayet star despite contributions from other massive companions.

    VFTS 682

    • A Wolf-Rayet star situated in the Large Magellanic Cloud, over 29 parsecs from R136.
    • Notable for having 150 Solar masses and 3.2 million Solar luminosities.

    Westerlund 2

    • An obscured young star cluster about 20,000 light-years away in Carina, estimated to be 1-2 million years old.
    • Features some of the hottest and most massive stars known.

    NGC 2867

    • An elliptical Type II planetary nebula located in the southern constellation Carina.

    NGC 3603-A1

    • A double-eclipsing binary star at the center of the HD 97950 cluster, notable for being among the most luminous stars.

    NGC 3603-B

    • A Wolf-Rayet star residing at the center of the HD 97950 cluster, classified as WN6h and highly luminous.

    NGC 3603-C

    • A single-lined spectroscopic binary system in the HD 97950 cluster, noted for its massive, luminous primary.

    R71

    • A luminous blue variable star located in the Large Magellanic Cloud with significant luminosity.

    R99

    • Another highly luminous star in the Large Magellanic Cloud, classified as a possible luminous blue variable.

    R136a1

    • One of the most massive and luminous stars at 215 Solar masses and 6.2 million Solar luminosities, found at the center of R136 in the Tarantula Nebula.

    R136a2

    • A prominent Wolf-Rayet star near the center of R136 with a confirmed mass of about 187 Solar masses and luminosity of 5.6 million.

    R136a3

    • Located near R136a1, this Wolf-Rayet star is one of the most massive and luminous, at 154 Solar masses.

    R136b

    • A highly luminous Wolf-Rayet star within the R136 cluster in the Large Magellanic Cloud.

    R136c

    • A massive star in R136, noted for its luminosity and temperature over 40,000 K.

    R145

    • A spectroscopic binary star in the Tarantula Nebula, both components noted for their exceptional luminosity.

    Superluminous Supernovae

    • 10 to 100 times brighter than typical supernovae, characterized by long rise times indicating significant mass.

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    Description

    Explore the fascinating world of Wolf-Rayet stars and their characteristics. This quiz covers key definitions and facts about these massive, rapidly rotating stars, including their identification and mass loss rates.

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